lightningd: expose/accept "style" parameter in routes.

Default is legacy.  If we have future styles, new strings can be defined,
but for now it's "tlv" or "legacy".

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

doc/lightning-getroute.7

@@ -113,8 +113,9 @@ factor for larger amounts, and is basically ignored for tiny ones\.
 
 On success, a "route" array is returned\. Each array element contains
 \fIid\fR (the node being routed through), \fImsatoshi\fR (the millisatoshis
-sent), \fIamount_msat\fR (the same, with \fImsat\fR appended), and \fIdelay\fR (the
+sent), \fIamount_msat\fR (the same, with \fImsat\fR appended), \fIdelay\fR (the
-number of blocks to timeout at this node)\.
+number of blocks to timeout at this node), and \fIstyle\fR (indicating
+the features which can be used for this hop)\.
 
 
 The final \fIid\fR will be the destination \fIid\fR given in the input\. The

doc/lightning-getroute.7.md

@@ -279,8 +279,9 @@ RETURN VALUE
 
 On success, a "route" array is returned. Each array element contains
 *id* (the node being routed through), *msatoshi* (the millisatoshis
-sent), *amount\_msat* (the same, with *msat* appended), and *delay* (the
+sent), *amount\_msat* (the same, with *msat* appended), *delay* (the
-number of blocks to timeout at this node).
+number of blocks to timeout at this node), and *style* (indicating
+the features which can be used for this hop).
 
 The final *id* will be the destination *id* given in the input. The
 difference between the first *msatoshi* minus the *msatoshi* given in

lightningd/gossip_control.c

@@ -303,6 +303,21 @@ static const struct json_command listnodes_command = {
 };
 AUTODATA(json_command, &listnodes_command);
 
+static void json_add_route_hop_style(struct json_stream *response,
+				     const char *fieldname,
+				     enum route_hop_style style)
+{
+	switch (style) {
+	case ROUTE_HOP_LEGACY:
+		json_add_string(response, fieldname, "legacy");
+		return;
+	case ROUTE_HOP_TLV:
+		json_add_string(response, fieldname, "tlv");
+		return;
+	}
+	fatal("Unknown route_hop_style %u", style);
+}
+
 /* Output a route hop */
 static void json_add_route_hop(struct json_stream *r, char const *n,
 			       const struct route_hop *h)
@@ -315,6 +330,7 @@ static void json_add_route_hop(struct json_stream *r, char const *n,
 	json_add_num(r, "direction", h->direction);
 	json_add_amount_msat_compat(r, h->amount, "msatoshi", "amount_msat");
 	json_add_num(r, "delay", h->delay);
+	json_add_route_hop_style(r, "style", h->style);
 	json_object_end(r);
 }
 

lightningd/pay.c

@@ -788,6 +788,27 @@ send_payment(struct lightningd *ld,
 JSON-RPC sendpay interface
 -----------------------------------------------------------------------------*/
 
+static struct command_result *param_route_hop_style(struct command *cmd,
+						    const char *name,
+						    const char *buffer,
+						    const jsmntok_t *tok,
+						    enum route_hop_style **style)
+{
+	*style = tal(cmd, enum route_hop_style);
+	if (json_tok_streq(buffer, tok, "legacy")) {
+		**style = ROUTE_HOP_LEGACY;
+		return NULL;
+	} else if (json_tok_streq(buffer, tok, "tlv")) {
+		**style = ROUTE_HOP_TLV;
+		return NULL;
+	}
+
+	return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
+			    "'%s' should be a legacy or tlv, not '%.*s'",
+			    name, json_tok_full_len(tok),
+			    json_tok_full(buffer, tok));
+}
+
 static struct command_result *json_sendpay(struct command *cmd,
 					   const char *buffer,
 					   const jsmntok_t *obj UNNEEDED,
@@ -846,6 +867,7 @@ static struct command_result *json_sendpay(struct command *cmd,
 		struct node_id *id;
 		struct short_channel_id *channel;
 		unsigned *delay, *direction;
+		enum route_hop_style *style;
 
 		if (!param(cmd, buffer, t,
 			   /* Only *one* of these is required */
@@ -856,6 +878,8 @@ static struct command_result *json_sendpay(struct command *cmd,
 			   p_opt("delay", param_number, &delay),
 			   p_opt("channel", param_short_channel_id, &channel),
 			   p_opt("direction", param_number, &direction),
+			   p_opt_def("style", param_route_hop_style, &style,
+				     ROUTE_HOP_LEGACY),
 			   NULL))
 			return command_param_failed();
 
@@ -884,6 +908,7 @@ static struct command_result *json_sendpay(struct command *cmd,
 		route[i].nodeid = *id;
 		route[i].delay = *delay;
 		route[i].channel_id = *channel;
+		route[i].style = *style;
 		/* FIXME: Actually ignored by sending code! */
 		route[i].direction = direction ? *direction : 0;
 	}